The invention concerns a drive for closing devices, such as gates and shutters, with variable speed output and a device for detecting a given position of the closing.
With respect to the operating of doors and gates, the use of variable-speed drives to impart motion to doors and gates is already known. For example, garage-door drives are known in which slow opening and closing speeds are used during the starting and stopping phase. A “gentle action” in the opening and closing of garage doors is thereby achieved. Initial slow acceleration of the garage door out of rest position to final motion speed, and its slowing down with appropriate deceleration before coming to a stop, is also ensured. This prevents a sudden crash of the garage door, which can lead to locking of the door and to annoying noise.
Additionally, frequency-converter-controlled drives that propel doors rapidly into open position and slowly into closed position by means of an appropriate frequency default are used in industry.
Additionally, a non-constant opening and closing movement of a closing device—for example a gate, a door, or a shutter—is also created by the design-related mechanical quality of the closing mechanism itself. The drive moment of the drive is transferred in a number of different ways to closing devices, that is, doors, gates, shutters, etc. Industrial gates are often activated by means of shaft drives that act directly on the rolling shaft. Similarly, in rolling gates in which the gate is wrapped spirally on a rolling shaft, this rolling shaft is operated directly by the drive. In sectional gates a torsion spring shaft is usually driven by winding drums. The cables are wound on the drums. The gate hanging on the cables is operated by means of the rotation of the drums.
When the aforementioned closing devices are activated, because of different mechanical winding principles of the closing devices different gate section speeds occur, if we assume here a constant speed output of the drive. In the case of the rolling gate, these different speeds are created by the spiral-shaped winding. In the case of a constant rolling-shaft speed, the rolling gate will initially close out of its wound-up state at a higher speed than is the case shortly before complete unwound state, since during the unrolling of the rolling gate the diameter of the spiral turn diminishes and thus the circumferential speed at which the rolling gate descends quickly decreases. Conversely, when the rolling gate is rolled up it moves more slowly, with a still smaller coil diameter, than is the case just before it reaches the maximum coil diameter.
In the case of the sectional gate, the differences in the opening and closing speeds result from the fact that for reasons of adjustment of gate weight and spring differential the cable drums are not always cylindrical, they can be conical or even a combination of cylindrical and conical. Here again, variable gate section speeds are thereby created with constant speed output.
While the above-described changes in speed in the opening and closing of closing devices are desirable, and are achieved by means of variable-speed drive of the closing devices, changes in speed during opening and closing of closing devices because of design-related characteristics are not desired.
It has been recognized that for safety reasons it is desirable to try to achieve defined and unchanging gate section speeds, except during the starting and stopping phases.
This leads to the task of perfecting a drive according to the generic model in such manner that closing devices can be operated, regardless of their construction, with defined, unchanging opening and closing speeds.